#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>

int main() {
	int a, b, c;
	//a = 1=(b = c) ;//WRONG
	//a = (a = b) = 1;//WRONG
	//将两个字符串合并
	char* r;
	char* s = "abc";
	char* t = "def";
	r = malloc(strlen(s) + strlen(t) + 1);//空字符占也算一个字符，需要+1
	if (!r) {
		perror("malloc");
		exit(1);
	}
	strcpy(r, s);
	strcat(r, s);
}